- Gregory Heffley
The main character, Greg, has trouble with family, friends, and his local middle school. He tries to fit in in his neighborhood and usually does not succeed. Facing many troubles, Greg attempts to handle them very creatively, but unfortunately his antics often backfire on him.
- Rowley Jefferson
Greg's best friend. He is always willing to do what Greg tells him and is going on vacations all the time, which annoys Greg. Rowley is a loyal friend from lots of people's perspectives.
- Manny Heffley
Greg's "spoiled" little brother. He never gets in trouble no matter what, even when he really deserves it. Manny is three years old.
- Rodrick Heffley
Rodrick is Greg's older brother and he never misses a chance to terrorize Greg. He is known for sleeping excessively and his rebellious attitude. Rodrick is part of a band called "The Löded Diper". Rodrick will do anything to embarrass Greg and will even wind up Manny to make everyone's life a misery.